1. Field of the Invention
The present invention relates to a graft copolymer excellent in a property to be colored and a thermoplastic resin composition with the same. More particularly, the present invention relates to a graft copolymer improved in a property to be colored with pigments and obtained by grafting a vinyl monomer onto a compound rubber comprising a modified polyorganosiloxane rubber and a polyalkyl (meth)acrylate rubber and a thermoplastic resin composition with the same.
2. Related Art
Various efforts have so far been made to improve the performance of impact resistant resins. In the course of the efforts, a technique of using a rubber having as low a T.sub.g as possible as the rubber component of impact resistant resins was developed, and a polyorganosiloxane rubber has been used as the rubber component. Examples of this technique is disclosed in Japanese Patent Application Kokai No. 61-138654.
This method, however, cannot improve a bad surface appearance like a dull surface arising from the polyorganosiloxane rubber. In order to improve this surface appearance, a compound rubber graft copolymer obtained by converting the polyorganosiloxane rubber and a polyacrylate rubber into a compound rubber and then graft-polymerizing a vinyl monomer onto this compound rubber is disclosed in U.S. Pat. No. 4,894,415, etc. However, when this compound rubber graft copolymer is used as the rubber component of impact resistant resins, the impact resistant resins thus obtained are poor in a property to be colored with pigments, so that they are of a low industrial value. Further, U.S. Pat. No. 4,888,388 discloses that when the compound rubber graft copolymer is used in a blend with polycarbonate or a polyester resin, the property to be colored with pigments is improved. However, this improvement is not satisfactory, a further improvement having been demanded.